Why can't you get Vista? Or Windows 7 for that matter? You can install XP 32-bit, but depending on how much RAM and what other type of hardware you have... it might be a waste. First of all, you won't have support for more than 4GB of RAM. Second, if you're planning on a DX10 or 11 video card, that won't have full support under XP either. You'll be much better served getting either Vista or Win 7 on new hardware. XP does support HT, but multi-core CPU support is better under Vista or 7.